One fundamental question in neuroscience is the relationship between brain and behavior. C. elegans is an excellent genetic model system for finding genes and elucidating pathways because of its sequenced genome and the abundance of molecular biology tools and mutants. Due to the simplicity of its nervous system, many breakthroughs have been made in C. elegans for understanding mechanisms in the neural basis of behavior. The current bottlenecks, however, are in the manual and labor-intensive techniques such as visual screens and laser ablation, often limiting the throughput of the experiments. Our long-term objective is to develop micro-scale devices to facilitate high-throughput studies, and use these techniques to understand how genes, properties of cells and circuits, and the environment together influence the behavior of an organism. Microfluidic chips are ideal for studies of C. elegans neuroscience because of the relevant length scales (~microns) and unique physical phenomena (e.g. laminar flow). In addition, microfluidics is also amenable for high-throughput experimentation and automation. The objective of this R21 project is to engineer microfluidic devices for large-scale live imaging and high-throughput laser neuron ablation in C. elegans in order to study an oxygen-sensing and behavior circuit. Because oxygen is an extremely important environmental cue for C. elegans, activities of neurons involved in this natural behavior will reveal fundamental mechanisms of the integration of sensory information. The hypothesis is that separate sets of sensory neurons are involved in two independent chemotactic strategies, and that these strategies are evoked in response to different environmental stimuli. The first component of this project is to develop high-throughput imaging and laser ablation techniques to perform circuit lesions. The second component is to use laser-ablated animals to decipher the roles of neurons in the sensory behavior. The approach is innovative because the technology developed here dramatically increases the capabilities and throughput of existing imaging and ablation tools. Furthermore, this work proposes and tests new sensory mechanisms that may have implications in many animal systems. The proposed research is significant because it is expected to expand the understanding of how sensory information is transduced and integrated in the nervous system, eventually producing behavior. In addition, besides the contribution to C. elegans sensory biology, the technologies are widely applicable to areas such as developmental biology, and to other organisms. [unreadable] [unreadable]